U.S. patent application number 12/253575 was filed with the patent office on 2009-04-23 for cooled blade for a turbomachine.
This patent application is currently assigned to SNECMA. Invention is credited to Jen-Michel Bernard Guimbard, Philippe Jean-Pierre Pabion, Jean-Luc Soupizon.
Application Number | 20090104018 12/253575 |
Document ID | / |
Family ID | 39717683 |
Filed Date | 2009-04-23 |
United States Patent
Application |
20090104018 |
Kind Code |
A1 |
Guimbard; Jen-Michel Bernard ;
et al. |
April 23, 2009 |
COOLED BLADE FOR A TURBOMACHINE
Abstract
The present invention relates to a cooled blade forming an
upstream guide vane element for a turbomachine, wherein the airfoil
comprises a longitudinal cavity with a first opening at one end and
a second opening at the other end, a tubular sleeve being housed in
the cavity with a first end in the first opening and a second end
in the second opening, first spacers on the side of the first end
and second spacers on the side of the second end of the sleeve
making a space between the outer face of the sleeve and the wall of
the cavity, the blade being arranged so that the sleeve is inserted
into the cavity through the first opening. The blade is
characterized in that the first spacers are secured to the sleeve
and the second spacers are secured to the wall of the cavity of the
airfoil. The invention makes it possible to mount the sleeve
despite an accentuated curvature of the profile of the airfoil.
Inventors: |
Guimbard; Jen-Michel Bernard;
(Cely en Biere, FR) ; Pabion; Philippe Jean-Pierre;
(Vaux le Penil, FR) ; Soupizon; Jean-Luc; (Vaux le
Penil, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
SNECMA
Paris
FR
|
Family ID: |
39717683 |
Appl. No.: |
12/253575 |
Filed: |
October 17, 2008 |
Current U.S.
Class: |
415/115 ;
29/889.721; 416/97R |
Current CPC
Class: |
F05D 2260/30 20130101;
F01D 5/189 20130101; Y10T 29/49341 20150115; F05D 2260/201
20130101; F05D 2230/60 20130101 |
Class at
Publication: |
415/115 ;
416/97.R; 29/889.721 |
International
Class: |
F01D 5/08 20060101
F01D005/08; B23P 15/04 20060101 B23P015/04 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 19, 2007 |
FR |
0707342 |
Claims
1. A cooled blade for a turbomachine, comprising a platform and an
airfoil, and comprising a cavity along the airfoil and the platform
with a first opening at one end and a second opening at the other
end, a tubular sleeve being housed in the cavity with a first end
in the first opening and a second end in the second opening, first
spacers on the side of the first end and second spacers on the side
of the second end of the sleeve creating a space between the outer
face of the sleeve and the wall of the cavity, the blade being
arranged so that the sleeve is inserted into the cavity through the
first opening, wherein the first spacers are secured to the sleeve
and the second spacers are secured to the wall of the cavity along
the airfoil.
2. The blade as claimed in the preceding claim wherein the first
spacers are placed in a direction forming an angle with the chord
of the blade.
3. The blade as claimed in claim 2 wherein the angle is zero.
4. The cooled blade as claimed in claim 1, wherein the sleeve is
formed of a metal sheet, the first spacers being bosses obtained by
deformation of the metal sheet.
5. The blade as claimed in the claim 4, wherein the bosses are
dome-shaped.
6. The blade as claimed in claim 1, wherein the first spacers are
arranged in the half of the sleeve situated on the side of the
first end.
7. The blade as claimed in claim 1, wherein the second spacers form
individual bosses.
8. The blade as claimed in claim 7, wherein the bosses are aligned
parallel to the chord.
9. The blade as claimed in claim 1, wherein the second spacers have
an elongated shape parallel to a chord of the blade.
10. The blade as claimed in claim 9, wherein the second spacers
form a continuous rail.
11. The blade as claimed in one of the preceding claims, wherein
the sleeve is perforated for cooling by air impact of the walls of
the airfoil.
12. The blade as claimed in claim 1, wherein the first opening is
on the outside of the gas stream.
13. The blade as claimed in claim 11, wherein the first opening is
on the inside of the gas stream.
14. A method for assembling the blade as claimed in one of the
preceding claims wherein the user places the sleeve in the cavity
by inserting it by its second end through the first opening.
15. An upstream guide vane element of a turbomachine comprising a
blade as claimed in one of claims 1 to 13.
16. A turbine comprising an upstream guide vane element as claimed
in claim 15.
17. A turbomachine comprising at least one blade as claimed in one
of claims 1 to 13.
Description
[0001] The present invention relates to the field of turbomachines
notably of gas turbine engines and its subject is more particularly
the cooled upstream guide vane element blades.
[0002] In a gas turbine engine, such as the turbojet with a front
turbofan 70 in FIG. 7, the incoming air is compressed in a
compressor before being mixed with a fuel and burned in a
combustion chamber. The hot gases produced in the chamber drive the
downstream turbine or turbines and are then ejected. The various
turbine stages 72 are separated by upstream guide vane elements
which guide the gas for an appropriate orientation when entering
the turbine. Because of the temperature of the gases, the blades,
notably those forming the upstream guide vane element at the
entrance of the high-pressure turbine and receiving the gases
directly from the combustion chamber, are subjected to very severe
operating conditions. Cooling means are arranged in the walls that
are in contact with the hot gases. The cooling is carried out by
forced convection or else by air impact on the inner faces of the
walls of the blades.
[0003] FIG. 1 represents, in longitudinal section, a blade 1
forming an upstream guide vane element of the prior art wherein the
cooling is provided by air impact from a tubular insert forming a
multipally perforated inner longitudinal sleeve 4, housed in the
cavity 6 of the blade. The airfoil of the blade 1 extends radially
between two platforms, a radially inner platform 3 and a radially
outer platform 2. The two platforms delimit the annular stream 5
for circulation of the driving gases. The stream is subdivided
circumferentially by the airfoils of the blades 1. The two
platforms and the airfoil form a single cast part. The sleeve 4 is
manufactured by forming a metal sheet and comprises small bosses 41
protruding on its outer face. The small bosses formed by swaging
are of a determined height and form spacers between the outer face
of the sleeve and the inner face of the cavity 6. They are
distributed between the ends of the sleeve. In this instance there
are two small bosses close to each end on each of the faces, on the
pressure side and suction side respectively. FIG. 2 shows in
longitudinal section parallel to the axis of the airfoil, the
arrangement of the bosses 41 on the sleeve. They keep the sleeve at
a distance from the walls of the airfoil in order to allow both the
impact of the air streams on the wall and the circulation of the
air in the space thus arranged. An opening 7 in the outer platform
supplies the sleeve 4 with cooling air drawn from the compressor
for example.
[0004] A portion of this air passes through the orifices 42 of the
sleeve and cools the wall of the blade by impact. This air then
flows downstream where it is discharged into the gas stream through
perforations provided along the wall of the trailing edge of the
airfoil. It should be noted that the inner face of the wall of the
airfoil may be provided with flow disrupting elements 61 which
promote the thermal exchanges between the air circulating in the
cavity and the wall. The rest of the air circulating radially
inside the sleeve is guided across the inner platform 3 up to a
tube 8 which directs it toward other turbomachine portions to be
cooled, such as the turbine disk or else the bearings.
[0005] The blade is open, at 9 and 10, to the two longitudinal ends
of the airfoil, respectively at its outer platform 2 and its inner
platform 3. On assembly, the sleeve that has previously been formed
is slid into the cavity 6 of the blade through the opening 9. The
sleeve is then secured to the blade by welding or brazing along its
edge in contact with the wall of the opening 9. The opposite
portion of the sleeve is guided into the inner opening 10 of the
blade which forms a slide in order to allow relative movements
between the blade and the sleeve. These longitudinal movements are
due to the temperature variations during the operation of the
turbomachine and to the fact that both parts differ by the nature
of the materials they are made of and the way they are
manufactured.
[0006] One particular embodiment of the sleeve inside the cavity is
described in the patent EP 1508670 in the name of the
applicant.
[0007] The performance of the turbomachine is enhanced by a
modification of the shape of the upstream guide vane elements. When
the airfoil of the upstream guide vane element defined
aerodynamically is twisted and has a profile having a twist about
its longitudinal axis, for example, and leading edges and trailing
edges that are not parallel with one another, difficulties are
encountered in mounting the sleeve in the cavity of the airfoil and
removing it therefrom. The representation of the geometric casings
of the cavity of the airfoil and of the outer face of the sleeve
with its small bosses shows, according to the envisaged
embodiments, zones of interference. The presence of these zones is
capable of making it impossible to install the sleeve inside the
cavity according to the prior art.
[0008] The applicant has therefore set itself the objective of
remedying this disadvantage.
[0009] For this reason, according to the invention, the cooled
blade of a turbomachine, comprising a platform and an airfoil, and
comprising a cavity along the airfoil and the platform with a first
opening at one end and a second opening at the other end, a tubular
sleeve being housed in the cavity with a first end in the first
opening and a second end in the second opening, first spacers on
the side of the first end and second spacers on the side of the
second end of the sleeve creating a space between the outer face of
the sleeve and the wall of the cavity, the blade being arranged so
that the sleeve is inserted into the cavity through the first
opening is remarkable for the fact that the first spacers are
secured to the sleeve and the second spacers are secured to the
wall of the cavity along the airfoil.
[0010] The solution of the invention makes it possible, with minor
modifications both to the metal sleeve and to the inner face of the
airfoil, to reserve a larger lateral clearance between the insert
and the wall of the cavity. This therefore gives greater freedom in
the choice of the geometry of the airfoil from an aerodynamic point
of view.
[0011] The result of this is a greater capacity to enhance the
output and performance of the turbine.
[0012] More particularly, the first spacers are placed in a
direction forming an angle with the chord of the blade. The angle
is zero in particular.
[0013] According to a preferred embodiment, the sleeve is formed of
a metal sheet, the first spacers being bosses obtained by
deformation of the metal sheet. The bosses are for example
dome-shaped.
[0014] The first spacers are advantageously arranged in the half of
the sleeve situated on the side of the first end, therefore leaving
a maximum lateral movement capacity, because of the space
requirement, while the first spacers are not engaged in the
cavity.
[0015] The second spacers form individual bosses. They are
preferably aligned parallel to the chord.
[0016] According to a variant, the second spacers have an elongated
shape parallel to a chord of the blade. More particularly, the
second spacers form a continuous rail, they thereby perform an
additional sealing function limiting the air leaks from inside the
sleeve through the space left free between the sleeve and the
slide.
[0017] The solution of the invention has a particular value when
the sleeve is perforated for cooling by air impact of the walls of
the airfoil.
[0018] The first opening is either on the outside of the gas stream
or on the inside of the gas stream.
[0019] The invention also relates to a method for assembling the
blade wherein the user places the sleeve in the cavity by inserting
it by its second end through the first opening.
[0020] A nonlimiting embodiment of the invention is described in
greater detail below with reference to the appended drawings in
which
[0021] FIG. 1 shows in longitudinal section a cooled upstream guide
vane element blade of the prior art with an inner sleeve for
distributing cooling air;
[0022] FIG. 2 is a longitudinal section of the blade of FIG. 1
showing the spacers arranged on the sleeve;
[0023] FIG. 3 is an example of a complex geometry blade
profile;
[0024] FIG. 4 is a view in longitudinal section of a blade
according to the invention;
[0025] FIG. 5 shows the step of assembling the blade wherein the
sleeve is inserted into the cavity of the airfoil;
[0026] FIG. 6 shows a variant embodiment of the spacers on the side
of the second opening of the airfoil;
[0027] FIG. 7 shows an engine capable of incorporating the blade
according to the invention.
[0028] The upstream guide vane element airfoil profile 20 of FIG. 3
shows a leading edge 21 and a trailing edge 28 whose curvatures
vary between the root of the airfoil and its tip. The longitudinal
directrix lines 23 and 24 for example, or else 26 and 27, also see
their curvature change. It is understood that a tubular inner
sleeve with the volume defined by this profile cannot be moved in
the longitudinal direction without the casings interfering in their
translation. Any interference corresponds to an impossibility of
movement.
[0029] In this case, installation or removal becomes impossible.
FIG. 3 illustrates this problem; the sleeve cannot be slid into the
cavity unless the blade has one and the same orientation of
curvature between the leading edge and the trailing edge. This is
not the case with the part of FIG. 3 where the curvatures of the
leading edge 21 and of the trailing edge 28 are inverted.
Specifically, searching for the preferred direction of
installation/removal is defined as follows. If, at each point, the
straight line tangential to the leading edge curve and the straight
line tangential to the trailing edge curve is considered, the
preferred direction would be the line bisecting the angle formed by
the two tangential straight lines, see tangent T2, tangent T3 and
average direction D in the figure. The translation in this
preferred direction is not allowed or is extremely limited in the
present case because of the change of the angle and therefore of
the bisecting line over the height of the airfoil. This change
results from the fact that there is inversion of the direction of
curvature between the curves 21 and 28, but also between the curves
of the intermediate directrix lines 23-24 on the one hand and 26-27
on the other hand.
[0030] The casing of the sleeve is defined by the bosses that
protrude on its surface. Because these bosses have a function as
spacers and to maintain a well-determined air gap, their casing is
very close to the geometric casing of the inner surface of the wall
of the airfoil. Any variation of curvature is therefore able to
prevent their relative movement.
[0031] The solution of the invention consisted in modifying the
distribution of the spacers between the sleeve and the airfoil.
FIG. 4 shows in longitudinal section a blade according to the
invention. The airfoil 20 extends between an inner platform 23 and
an outer platform 22. The two platforms are the borders of the
annular stream traveled by the driving gases. The sleeve 24 inside
the cavity 26 of the airfoil is welded or brazed by its first end
243 to the wall of the first opening 29. This opening 29 is made in
the wall of the outer platform 22. The other end 244 of the sleeve
is engaged in the second opening 30 made in the inner platform 23.
Being secured to the airfoil by one end, 243, and free at its other
end, 244, the two parts may expand independently of one
another.
[0032] On the side of its first end 243, the sleeve comprises
bosses formed by deformation of the metal sheet. These bosses form
spacers keeping the wall of the sleeve at a distance from the wall
of the cavity. They are for example aligned parallel to the
direction of the chord of the blade.
[0033] The sleeve does not comprise other bosses as is clearly seen
in FIG. 4.
[0034] Protrusions 25 arranged on the inner face of the wall of the
airfoil 20 form spacers and keep the sleeve away from the wall of
the cavity. These protrusions are situated close to the second
opening 30. They are made with the blade by casting. Preferably
they form spacers of the same height as the bosses 241 so that the
space for the circulation of cooling air is the same between the
root of the airfoil and its tip. However, the solution of the
invention allows a different arrangement of the spacers. These
protrusions may be parallel to a chord of the blade. Advantageously
they are elongated in shape.
[0035] In operation, the cooling air is injected through the first
end 243 into the tubular channel of the sleeve; a portion of this
air traverses the sleeve through the perforations 242 and divides
into thin jets which cool the wall of the airfoil 20. The air then
circulates in the space between the sleeve and the wall in order to
be ejected toward the trailing edge. Another portion of the air
flows through the second end and is guided toward another cooling
circuit.
[0036] FIG. 5 shows the value of the solution at the time of
assembly. The sleeve is inserted by its second end 244 into the
cavity 26 through the first opening 29 of the blade. Since the
lower portion of the sleeve, in the figure, does not comprise any
transverse protrusion, the user has a certain lateral movement
capacity. This capacity is retained until the second end is engaged
in the space defined by the protrusions 25. These protrusions are
placed close to the second opening 30. The sleeve, at this moment,
is close to its engagement in the second opening. Its movement is
virtually completed.
[0037] FIG. 6 shows a variant embodiment. It represents only the
portion of the airfoil 40 close to the second opening 41. The
sleeve 34 is engaged by its second end 344 in the second opening 41
of the airfoil. The bosses have been replaced by a rail 35 which
runs over the whole periphery, preferably parallel to the plane of
the opening 41. Its function is to form a chicane limiting the
circulation of the air from one side of the rail to the other. The
value of this variant comes from the air leaks which occur between
the sleeve at 344 and the wall of the airfoil in the slide of the
opening 41. Specifically, in order not to prevent the sleeve from
sliding freely in the slide as a result of the dimensional
variations between them, a certain clearance must be maintained
which is the cause of the air leaks. A portion F of this air is
diverted from the planned direction D. The movement of this air in
the space between the sleeve and the airfoil is undesirable because
it is lost without having contributed to the cooling. The
arrangement of such a chicane therefore helps to contain the air
inside the sleeve.
* * * * *